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public synchronized void start() {
    /**
     * This method is not invoked for the main method thread or "system"
     * group threads created/set up by the VM. Any new functionality added
     * to this method in the future may have to also be added to the VM.
     *
     * A zero status value corresponds to state "NEW".
     */
    if (threadStatus != 0)
        throw new IllegalThreadStateException();

    /* Notify the group that this thread is about to be started
     * so that it can be added to the group's list of threads
     * and the group's unstarted count can be decremented. */
    group.add(this);

    boolean started = false;
    try {
        start0();
        started = true;
    } finally {
        try {
            if (!started) {
                group.threadStartFailed(this);
            }
        } catch (Throwable ignore) {
            /* do nothing. If start0 threw a Throwable then
              it will be passed up the call stack */
        }
    }
}

private native void start0();

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package com.gupao.juc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class C {
    public static void main(String[] args) {
        data3 data3 = new data3();
        new Thread(()->{data3.printA();},"A").start();
        new Thread(()->{data3.printB();},"B").start();
        new Thread(()->{data3.printC();},"C").start();
    }

}
class data3{
    private Lock lock = new ReentrantLock();
    Condition condition1 = lock.newCondition();
    Condition condition2 = lock.newCondition();
    Condition condition3 = lock.newCondition();
    private int number = 1;
    public void printA(){
        lock.lock();
        try{
            while(number!=1){
                condition1.await();
            }
            System.out.println(Thread.currentThread().getName());
            number++;
            condition2.signal();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
    public void printB(){
        lock.lock();
        try{
            while(number!=2){
                condition1.await();
            }
            System.out.println(Thread.currentThread().getName());
            number++;
            condition3.signal();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
    public void printC(){
        lock.lock();
        try{
            while(number!=3){
                condition1.await();
            }
            System.out.println(Thread.currentThread().getName());
            number = 1;
            condition1.signal();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
}